GB652266A and EP1541003B1 show spring suspension devices of a type which is used in an agricultural implement and which comprises an inner square tube disposed in an outer casing, wherein the square tube and the casing are rotated through 45° in relation to each other and rubber rods are disposed in the substantially triangular spaces which are formed between the outer surface of the square tube and the inner surface of the casing.
SE534357C2 shows a similar spring suspension device, which substantially consists of a triangular tube and a casing of triangular cross section, which are rotated through 60° relative to each other and are provided with rubber rods in the formed triangular spaces.
Suspension devices of the above type are usually placed such that the square tube or the triangular tube extends substantially horizontally and perpendicularly to a direction of advance of the agricultural implement, so that a spring movement is performed in a vertical plane which is parallel with the direction of advance.
In some applications, it would be desirable to provide spring suspension devices which are stiffer, viewed in a direction perpendicular to the direction of advance.
In other applications, it would be desirable to provide spring suspension devices which, given a certain spring characteristic in the vertical plane, occupy less space in a direction perpendicular to the direction of advance.
In other applications, it would be desirable to provide spring suspension devices which have improved damping.
To this end, it is desirable to provide spring suspension devices whose spring characteristic in the lateral direction is less dependent on the spring characteristic in the direction of advance.